Door switch for electrical apparatus

ABSTRACT

A door switch designed primarily for use with an electrical apparatus or appliance and having a double action safety operating structure is disclosed and includes a switching plate which is movable by the opening and closing of a door of the apparatus, a stopper which holds the switching plate in a predetermined position when the door is closed, means for releasing the holding of the switching plate by the stopper and a relay which begins to operate following the releasing movement of the switching plate.

United States Patent [191 Inagawa DOOR SWITCH FOR ELECTRICAL APPARATUS [75 Inventor: Takashi Inagawa, Ichinomiya, Japan [73] Assignee: Tokyo Shibaura Electric Co.

Limited, Tokyo, Japan [22] Filed: Nov. 10, 1972 [21] Appl. No.: 305,362

[ Mar. 26, 1974 2,360,227 10/1944 Hemphill ZOO/61.62 2,759,485 8/1956 Guth ZOO/61.62 X 3,091,675 5/1963 Sholtes ZOO/61.62

Primary Examiner-James R. Scott Attorney, Agent, or Firm-Oblon, Fisher, Spivak, Mc- Clelland & Maier [5 7] ABSTRACT A door switch designed primarily for use with an electrical apparatus or appliance and having a double action safety operating structure is disclosed and includes a switching plate which is movable by the opening and closing of a door of the apparatus, a stopper which holds the switching plate in a predetermined position when the door is closed, means for releasing the holding of the switching plate by the stopper and a relay which begins to operate following the releasing movement of the switching plate.

3 Claims, 9 Drawing Figures EAIENTEU R2 6 1974 SHEET 1 [IF 3 lllllll l I 1 DOOR SWITCH FOR ELECTRICAL APPARATUS BACKGROUND OF THE INVENTION 1. Field Of The Invention The present invention relates to a door switch for an electrical appliance which has a double safety construction for preventing misworking of the apparatus through an unintentional closing of the door thereof, or such closing which was not intended to place the apparatus in an operative state.

2. Description Of The Prior Art In an electric apparatus, such as an electric dryer or an electric oven, on and off-operation of the apparatus is often achieved corresponding to the closing and opening of a door thereof which is appropriately mounted to the apparatus. A movable tip of a microswitch is mounted opposite one side of the door, and the microswitch operates to turn the apparatus to its ON" state by the pressing of the movable tip being caused by the closing action of the door. The apparatus is automatically turned to its OFF state by releasing the movable tip from its depressed state, and this is accomplished merely by opening the door.

The electric apparatus, such as a dryer or oven, being provided with such a door switch automatically begins to operate immediately upon closing the door, and thus it will also start unexpectedly by any unintended pushing or closing of the door by an operator, for example, by children at play. This is undesirable, of course, as such might prove to be dangerous for the operators or the children.

Thus, a need exists for a door switch for doors of this type apparatus which does not operate only by the closing and opening action of the door to place the apparatus, respectively, in or out of its operative state, but which requires another manual operation.

SUMMARY OF THE INVENTION Accordingly it is an object of the present invention to provide a new and unique door switch forenabling the safer handling of an electrical apparatus.

Another object of the present invention is to provide a new and improved double safety door switch for an electrical apparatus.

Briefly, in accordance with the present invention, the foregoing and other objects are attained according to one aspect thereof through the provision of a moving member which moves according to the opening and closing action of a door, a switching plate which is movable according to the movement of the moving member, a stopper which holds the switching plate at a predetermined position, a button which moves the stopper and thereby releases the holding of the switching plate by the stopper, and a microswitch which operates along with the releasing movement of the switching plate.

BRIEF DESCRIPTION OF DRAWINGS O Other OIJJCCIS, features and attendant advantages of 6 the present invention will be more fully appreciated by those skilled in the art as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof and wherein:

FIG. 1 is a perspective view of an electric dryer, partly broken away, to which an embodiment of the door switch of the present invention is attached;

FIG. 2 is a vertical sectional view of the electric dryer shown in FIG. 1 to which an embodiment of the door switch of the present invention is attached;

FIG. 3 is a perspective view of the preferred embodiment of the door switch of the present invention;

FIG. 4A is a side view, partly in section, of the embodiment of the door switch of the present invention shown in FIG. 3 and in its OFF state;

FIG. 4B is a front view of the embodiment of the door switch of the present invention shown in FIG. 4A, also in its OFF state;

FIG. 5A is a side view, partly in section, of the embodiment of the present invention shown in FIGS. 3 and 4, but showing its condition when the door of the electrical appliance to which it is attached is closed;

FIG. 5B is a front view of the embodiment of the door switch of the present invention showing the state thereof when the door of the electrical apparatus to which it is attached is closed;

FIG. 6A is a side view, partly in section, of the embodiment of the present invention shown in the previous Figures, but in its ON state;

FIG. 6B is a front view of the embodiment of the door switch of the present invention, also in its ON state.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings, and more particularly to FIGS. 1 and 2 thereof, wherein an electric dryer with a preferred embodiment of a door switch according to the present invention is shown, a housing 10 of the electric dryer has an opening 12, and a door 14, with a handle 16, is mounted to the housing 10 by hinges 18 for placing clothing in the dryer and removing the same therefrom. A drum 20 disposed in the housing 10 has an opening 22 at its front end and is rotatably mounted to a plate 30 which works for providing an effective passageway for heated air to be led to the drum 20. A rear end protruding portion 24 of the drum 20 is also rotatably mounted to a fan casing 32. The drum 20 has numerous intake holes 26 at the peripheral portion of the front end and numerous exhausting holes 28 at the central portion of the rear end. The air is heated by an electric heater 34 and is introduced into the drum 20 through the intake holes 26 and exhausted through the exhausting holes 28 by a fan 36 disposed in fan casing 32.

An electric motor 38 is fixed on a bottom plate of the housing 10 and pulleys 40 and 42 are fixed at the respective opposite ends of a rotor shaft 44 of the motor 38 extending from the opposing ends thereof. A drum driving belt 46 is disposed about the outer peripheral portion of the drum 20 and the pulley 40 through a tension pulley 48, enabling the drum 20 to be rotated. A fan driving belt 50 is arranged between the motor pulley 42 and a pulley 52, which is fixed to a shaft 54 of the fan, for driving the fan 36.

Thus, when the motor 38 is turned to its ON" state, the drum 20 and the fan 52 will rotate, and the air heated by the heater 34 is thereby introduced into the drum 20 through the intake holes 26 to dry the clothing in the drum 20. The air in the drum 20 is exhausted through a lint filter 56 disposed in front of the exhausting holes 28 at the rear of the drum 20 and then out through an exhausting duct 58 to the exterior of the housing 10.

Operation of the dryer is accomplished by starting the motor 38 through setting the time for drying by adjusting a timer 60, closing the door 14 and pushing button rod 114 of a door switch 70.

The particular construction of the door switch 70 which embodies the present invention is now explained with reference to FIGS. 3, 4A and 4B.

A base plate 72 is fixed to a front panel of the casing with screws or the like. A switching plate 74 is rotatably mounted on the back side of the base plate 72 for rotation about a pivot pin 76 and is provided with two backwardly bent parallel portions, one being a reacting portion 78 and the other being an acting portion 80. The acting portion 80 has an outstanding bent holding portion 82. A moving rod 84 is coupled to the reacting portion 78 disposed at the bottom of the reacting portion and to a supporting portion 86, which is formed at a lower portion of the base plate 72, being bent backwardly therefrom in substantially parallel relation to the reacting portion 78, through holes suitably formed therein. A top or head portion 88 of the moving rod 84 is pushed by the closing action of the door 14, being contacted by a pushing member 90 formed on the inside edge of the hinged side of the door 14. Two coil springs 92 and 94 are disposed in surrounding relation about the moving rod 84, the coil spring 92 being held between the supporting portion 86 of the base plate 72 and the top or head portion 88 of the moving rod 84 and the coil spring 94 being held between the reacting portion 78 of the switching plate 74 and an annular stop member 96 tightly secured to the moving rod 84 adjacent the supporting portion 86 of the base plate 72. Another stop member 98 which is tightly fixed to the moving rod 84 on the side of the reacting portion 78 facing away from the supporting portion 86 prevents the moving rod 84 from being pulled out of the hole formed in the reacting portion 78 ofthe switching plate 74.

A microswitch 100 is shown being fixed on the base plate 72 through an insulating board 102 with screws 104 so that a reacting tip 106 of the microswitch 100 faces in the direction of the acting portion 80 of the switching plate 74. A space to allow a small rotation of the switching plate 74 is formed between the acting portion 80 and reacting tip 106. The microswitch 100 has two terminals 108 which are connected to the motor 38 and the heater 34 through suitable lead wires 110, shown in phantom lines in FIGS. 3 and 4B.

The base plate 72 is provided with a U-shaped bent portion 112, and the push button rod 114 is loosely coupled to the U-shaped bent portion 112 and tightly coupled to another U-shaped stopper 116 disposed in parallel relationship therewith. One side wall of the bent portion 112 is disposed between the two side walls of the U-shaped stopper 116 through a suitable receiving means provided therein. Reciprocable movement of the push button rod 114 is made easy by the action ofa bushing 118 and sliding out of the push button rod 114 from the receiving holes provided therefor in the bent portions 112 and 116 is prevented by a flange 120 disposed thereon and situated between the bushing 118 and the forward side of bent portion 116 and a stop ring 122 disposed on the push button rod 114 and situated to the rear of the bent portion 116. A coil spring 124 is disposed between the forward side wall of the U- shaped stopper 116 and the sidewall of the U-shaped bent portion 112 disposed within the stopper 116 to provide the push button rod 114 and the U-shaped stopper 1 16 with recovering energy when the push button rod 114 is pushed and released.

The base leg of the U-shaped stopper 116 has an elongated downwardly extending portion 126 designed to be positioned in between the acting portion of the base plate 72 and the microswitch 100. The elongated portion 126 has a projection 128 extending toward the acting portion 80 to provide a sufficient spacing to prevent the reacting tip 106 of the microswitch 100 from being pressed when the elongated portion 126 is at the position shown in FIG. 4B.

FIGS. 4A and 4B show the apparatus in the state where the door 14 is open. The moving rod 84 is thus not being pressed by the pushing member of the door 14 and is energized to move to the right in FIG. 4B because of the spring action of the coil spring 92. The switching plate 74 which is tightly connected to the moving rod 84 by the stopping member 98 and the coil spring 94 is given a counter-clockwise direction force, as viewed in FIG. 4B. Therefore, the reacting tip 106 of the microswitch is not pushed and the motor 38 and the heater 34 are not operative.

When the door 14 is closed, as is shown in FIGS. 5A and 5B, the pushing member 90 of the door 14 presses the moving rod 84 to the left, as seen in FIG. 5A. The switching board 74 is thus moved in a clockwise direction about the pivot 76 and the acting portion 80 moves toward the reacting tip 106 of the microswitch 100. This movement, however, is stopped by the downwardly extending projection 128 of the stopper 116 and the microswitch 100 is accordingly not yet actuated. Accordingly, the motor 38 and the heater 34 do not become operative. In this condition, the coil springs 92 and 94 store the energy to move the moving rod 84 to its former position, as is illustrated in FIGS. 4A and 4B.

When the push button rod 114 is pushed, under the aforementioned conditions, as is shown in FIGS. 6A and 6B, the stopper 116 is moved toward the right, as seen in FIG. 6A, by the flange of the push button rod 114 to release the engagement of the acting portion 80 of the switching plate 74 and the projection 128 of the stopper 116, by moving the projection beyond the area of the acting portion 80 and to that of the portion 82 thereof. Thus, the switching plate 74 rotates in the clockwise direction under the biasing force of the coil spring 94 and the acting portion 80 then presses the reacting tip 106 of the microswitch 100. The microswitch 100 thus makes it possible to supply electric current to the motor 38 and the heater 34, and the dryer becomes operative.

A recovering movement of the stopper 116 by the spring action of coil spring 124 is prevented by the coupling of the outwardly bent holding portion 82 and the projection 128 of the stopper 116. The stopper 116 remains in this state after the pressure on the push button rod 114 of the fingers of an operator is released.

When the door 14 is opened for taking out the dried clothing, the moving rod 84 is released from the depressed condition by the pushing member 90 of the door 14 and it returns to the original position, which is illustrated in FIGS. 4A and 4B, under the force of the coil springs 92 and 96. Accordingly, the switching plate 74 rotates in the counter-clockwise direction to release the engagement of the acting portion 80 and the reacting tip 106 of the microswitch 100, whereby the microswitch 100 stops the supply of electric current to the motor 38 and the heater 34. The stopper 116 is returned to its original state by the spring action of the coil spring 124, as is illustrated in FIGS. 4A and 48, because the coupling of the holding portion 82 and the projection 128 is released according with the recovering movement of the switching plate 74.

As is described hereinbefore, the microswitch 100 becomes actuated only with the double action of doorclosing and start button-pushing. Therefore, the door switch of the present invention prevents mis-starting of the apparatus caused by an unintended action. Of course, the door switch of the present invention may be used not only for an electric dryer, but also for many other electric apparatuses which have similar doors.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

What is claimed as new and desired to be secured by letters patent of the United States is:

l. A door switch for an electrically operated apparatus comprising:

moving member means mounted within said apparatus and movable by the opening and closing of a door of said apparatus;

a switching plate rotatably mounted in said apparatus and being movable by said moving member means;

energy storage means engaging said moving member means and said switching plate for storing energy upon closure of said door, said stored energy tending to rotate said switching plate;

a stopper means for holding said switching plate in a predetermined position against said energy stored by said energy storage means when said door is closed;

means for releasing the holding action of said stopper means and for releasing said stored energy; and

a switch operable by said switching plate upon release of said stored energy by said releasing means for causing said apparatus to become operative.

2. A door switch for an electrically operated apparatus comprising:

moving member means mounted within said apparatus and movable by the opening and closing of a door of said apparatus;

a switching plate rotatably mounted in said apparatus and being movable by said moving member means;

a stopper means for normally retaining said switching plate in a predetermined position when said door is closed;

means engaging said stopper means for releasing said stopper means; and

a switch operable by said switching plate upon release thereof by said releasing means for causing said apparatus to become operative; and,

wherein said moving member means includes;

an elongate rod member having one end thereof extending through said switching plate;

first biasing means for urging said rod member to normally move in one axial direction;

the other end of said rod member being engageable by said door upon the closing of said door and being movable thereby in the other direction against the urging force of said first biasing means.

stop means on said one end of said rod member for limiting the movement of said rod member in said one direction and thereby preventing said rod member from being removed from said switching plate by said first biasing means; and

second biasing means between said rod member and said switching plate for normally urging said switching plate to move in the direction of said stop means on said rod member.

3. A door switch according to claim 4, wherein said stopper means for holding said switching plate comprises:

a movable stop member normally disposed in a given position between said relay and said switching plate to prevent engagement therebetween; and

third biasing means for normally maintaining said movable stop member in said given position; and

said releasing means is a manually operable member connected to said movable stop member for moving said stop member against the force of said third biasing means to a position wherein said movable stop member does not prevent engagement of said switching plate with said relay. 

1. A door switch for an electrically operated apparatus comprising: moving member means mounted within said apparatus and movable By the opening and closing of a door of said apparatus; a switching plate rotatably mounted in said apparatus and being movable by said moving member means; energy storage means engaging said moving member means and said switching plate for storing energy upon closure of said door, said stored energy tending to rotate said switching plate; a stopper means for holding said switching plate in a predetermined position against said energy stored by said energy storage means when said door is closed; means for releasing the holding action of said stopper means and for releasing said stored energy; and a switch operable by said switching plate upon release of said stored energy by said releasing means for causing said apparatus to become operative.
 2. A door switch for an electrically operated apparatus comprising: moving member means mounted within said apparatus and movable by the opening and closing of a door of said apparatus; a switching plate rotatably mounted in said apparatus and being movable by said moving member means; a stopper means for normally retaining said switching plate in a predetermined position when said door is closed; means engaging said stopper means for releasing said stopper means; and a switch operable by said switching plate upon release thereof by said releasing means for causing said apparatus to become operative; and, wherein said moving member means includes; an elongate rod member having one end thereof extending through said switching plate; first biasing means for urging said rod member to normally move in one axial direction; the other end of said rod member being engageable by said door upon the closing of said door and being movable thereby in the other direction against the urging force of said first biasing means. stop means on said one end of said rod member for limiting the movement of said rod member in said one direction and thereby preventing said rod member from being removed from said switching plate by said first biasing means; and second biasing means between said rod member and said switching plate for normally urging said switching plate to move in the direction of said stop means on said rod member.
 3. A door switch according to claim 4, wherein said stopper means for holding said switching plate comprises: a movable stop member normally disposed in a given position between said relay and said switching plate to prevent engagement therebetween; and third biasing means for normally maintaining said movable stop member in said given position; and said releasing means is a manually operable member connected to said movable stop member for moving said stop member against the force of said third biasing means to a position wherein said movable stop member does not prevent engagement of said switching plate with said relay. 